<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        *{
            padding: 0;
            margin: 0;
        }
        .triangle{
            width: 0;
            height: 0;
            border-bottom: 100px solid black;
            border-left:100px solid transparent;
            border-top:100px solid  transparent;
            border-right:100px solid  black;
        }
    </style>
</head>
<body>
    <div class="triangle"></div>
</body>
</html>